Subsequent to manufacturing of semiconductor devices, various characteristics of elements are tested for purposes of detecting process defects and characteristic variations and of implementing process control. When conducting theses tests, test-purpose circuits and patterns referred to as Test Element Group (TEG) are used. The TEG reflects the characteristics of elements within a semiconductor integrated circuit that operates actually, including transistors, resistors, capacitors and wirings. It is therefore possible to estimate the characteristics of elements within the semiconductor integrated circuit by measuring the characteristics of the TEG.
The TEG is usually formed within a chip-forming region or a scribe line of a semiconductor wafer concurrently with elements in a semiconductor integrated circuit. In other words, the TEG is formed by, for example, a photolithography technique using a reticle (mask for exposure) whereon patterns for elements and TEGs are formed. FIGS. 10A and 10B illustrate conventional layouts of TEGs.
FIG. 10A illustrates an example of transferring a single chip in one shot. In this example, pads 102 are formed in the periphery of each chip 101 and TEGs 103 are formed in the four corners. FIG. 10B illustrates an example of transferring a plurality of chips in one shot. In this example, TEGs 113 are formed within a scribe line between chips 111.
Conventionally, monitoring tests are conducted using such TEGs as described above to determine whether or not a manufactured semiconductor device operates normally. Then, the manufacturing process is reviewed according to the results of determination if any failure is found. In Patent Documents 1 to 4, various examples of TEGs and the like are cited.
However, even if the results of monitoring tests or probe tests (PT) using conventional TEGs are favorable, some semiconductor devices may suffer an operational failure as time advances. In order to investigate the cause of the failure in such a case, the cross section of the semiconductor device must be examined. In some cases, however, it is not possible to investigate the cause even if such an examination is carried out. This results in a failure to identify the cause and establish countermeasures. The problem thus remains unsolvable for a long period of time.    Patent document 1: Japanese Patent Application Laid-Open No. Sho 60-83344    Patent document 2: Japanese Patent Application Laid-Open No. Sho 60-109240    Patent document 3: Japanese Patent Application Laid-Open No. Hei 01-225138    Patent document 4: Japanese Patent Application Laid-Open No. 2000-332077